diff --git a/src/main/java/de/app/fivegla/integration/fiware/SubscriptionIntegrationService.java b/src/main/java/de/app/fivegla/integration/fiware/SubscriptionIntegrationService.java
index 06ed224..7ec8cb9 100644
--- a/src/main/java/de/app/fivegla/integration/fiware/SubscriptionIntegrationService.java
+++ b/src/main/java/de/app/fivegla/integration/fiware/SubscriptionIntegrationService.java
@@ -47,38 +47,85 @@ public SubscriptionIntegrationService(String contextBrokerUrl, List<String> noti
      *                    each representing a different type.
      */
     public void subscribe(Tenant tenant, EntityType... entityTypes) {
-        removeAll(tenant); // FIXME adjust and update subscriptions instead of removing all
-        var httpClient = HttpClient.newHttpClient();
-        var subscriptions = createSubscriptions(entityTypes);
-        for (var subscription : subscriptions) {
-            String json = toJson(subscription);
-            log.debug("Creating subscription: " + json);
+        List<Subscription> allExistingSubscriptions = findAll(tenant);
+        if (!allExistingSubscriptions.isEmpty()) {
+            updateExistingSubscriptions(tenant, allExistingSubscriptions, entityTypes);
+        } else {
+            var httpClient = HttpClient.newHttpClient();
+            var subscriptions = createSubscriptions(entityTypes);
+            for (var subscription : subscriptions) {
+                String json = toJson(subscription);
+                log.debug("Creating subscription: {}", json);
+                var httpRequest = HttpRequest.newBuilder()
+                        .uri(URI.create(contextBrokerUrlForCommands() + "/subscriptions"))
+                        .header("Content-Type", "application/json")
+                        .header(CustomHeader.FIWARE_SERVICE, tenant.getTenantId())
+                        .POST(HttpRequest.BodyPublishers.ofString(json)).build();
+                try {
+                    var response = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
+                    if (response.statusCode() != 201) {
+                        log.error("Could not create subscription. Response: {}", response.body());
+                        throw new BusinessException(ErrorMessage.builder()
+                                .message("Could not create subscription, there was an error from FIWARE.")
+                                .error(Error.FIWARE_INTEGRATION_LAYER_ERROR)
+                                .build());
+                    } else {
+                        log.info("Subscription created/updated successfully.");
+                    }
+                } catch (Exception e) {
+                    log.error("Could not create subscription.", e);
+                    throw new BusinessException(ErrorMessage.builder()
+                            .message("Could not create subscription.")
+                            .error(Error.FIWARE_INTEGRATION_LAYER_ERROR)
+                            .build());
+                }
+            }
+        }
+    }
+
+    private void updateExistingSubscriptions(Tenant tenant, List<Subscription> allExistingSubscriptions, EntityType[] newEntityTypes) {
+        allExistingSubscriptions.forEach(subscription -> {
+            var newSubscription = Subscription.builder()
+                    .id(subscription.getId())
+                    .description(subscription.getDescription())
+                    .subject(Subject.builder()
+                            .entities(createSubscriptionEntities(newEntityTypes))
+                            .build())
+                    .notification(Notification.builder()
+                            .http(Http.builder()
+                                    .url(subscription.getNotification().getHttp().getUrl())
+                                    .build())
+                            .build())
+                    .expires(subscription.getExpires())
+                    .status(subscription.getStatus())
+                    .build();
+            var httpClient = HttpClient.newHttpClient();
+            String json = toJson(newSubscription);
+            log.debug("Updating subscription: {}", json);
             var httpRequest = HttpRequest.newBuilder()
-                    .uri(URI.create(contextBrokerUrlForCommands() + "/subscriptions"))
+                    .uri(URI.create(contextBrokerUrlForCommands() + "/subscriptions/" + subscription.getId()))
                     .header("Content-Type", "application/json")
                     .header(CustomHeader.FIWARE_SERVICE, tenant.getTenantId())
-                    .POST(HttpRequest.BodyPublishers.ofString(json)).build();
+                    .PUT(HttpRequest.BodyPublishers.ofString(json)).build();
             try {
                 var response = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
                 if (response.statusCode() != 201) {
-                    log.error("Could not create subscription. Response: {}", response.body());
-                    log.debug("Request: {}", json);
-                    log.debug("Response: {}", response.body());
+                    log.error("Could not update subscription. Response: {}", response.body());
                     throw new BusinessException(ErrorMessage.builder()
-                            .message("Could not create subscription, there was an error from FIWARE.")
+                            .message("Could not update subscription, there was an error from FIWARE.")
                             .error(Error.FIWARE_INTEGRATION_LAYER_ERROR)
                             .build());
                 } else {
-                    log.info("Subscription created/updated successfully.");
+                    log.info("Subscription updated successfully.");
                 }
             } catch (Exception e) {
-                log.error("Could not create subscription.", e);
+                log.error("Could not update subscription.", e);
                 throw new BusinessException(ErrorMessage.builder()
-                        .message("Could not create subscription.")
+                        .message("Could not update subscription.")
                         .error(Error.FIWARE_INTEGRATION_LAYER_ERROR)
                         .build());
             }
-        }
+        });
     }
 
     private List<Subscription> createSubscriptions(EntityType... entityTypes) {